#!/usr/bin/env node

const stdin = process.stdin,
      stdout = process.stdout;


//stdin.on('data',(data)=> {
  //stdout.write(data.toString('utf8').toUpperCase()); 
  ////console.log(data)
//})

//stdin.push('hello');
//stdin.push('world\n');

for (let c='a'.charCodeAt(0); c<='z'.charCodeAt(0);c++){
  stdin.push(String.fromCharCode(c));
}
//终止
stdin.push(null);

stdin.pipe(stdout);     


